ActionScript for Flash MX: The Definitive Guide, Second Edition

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Copyright © 2007 O’Reilly & Associates, Inc. All rights reserved.

Creating and Categorizing Data

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A literal expression (or literal for short) is a series of letters, numbers, and punctua-

tion that is the datum. A data literal is a verbatim description of data in a program’s

source code. This contrasts with a variable, which is merely a container that holds a

datum. Each datatype defines its own rules for the creation of literals. For example,

string literals are enclosed in quotes, whereas numeric literals are not. Here are some

examples of literals:

"loading...please wait" // A string literal

1.51 // A numeric literal

["jane", "jonathan"] // An array literal

{x: 10, y: 15} // An object literal

Note that movie clips cannot be represented by literals but are referred to by instance

names.

We can also generate data programmatically with a complex expression. Complex

expressions are phrases of code with a value that must be calculated or computed,

not taken literally. The calculated value is the datum being represented. For exam-

ple, each of these complex expressions results in a single datum:

1999 + 1 // Yields the numeric datum 2000

"1999" + "1" // Yields the string datum "19991"

"hi " + "ma!" // Yields the string datum "hi ma!"

firstName // Yields the value of the variable firstName

_currentframe // Yields the frame number of the playhead's current ...